Implement batch creation

src/batch.rs

@@ -8,6 +8,79 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use atlas::Atlas;
+use compute_shader::buffer::{Buffer, BufferData, HostAllocatedData, Protection};
+use compute_shader::device::Device;
+use glyph_buffer::GlyphBufferBuilder;
+use std::u16;
+
+const POINTS_PER_SEGMENT: u32 = 32;
+
+pub struct BatchBuilder {
+    pub atlas: Atlas,
+    pub indices: Vec<u16>,
+    pub images: Vec<ImageDescriptor>,
+    pub point_count: u32,
+}
+
+impl BatchBuilder {
+    /// FIXME(pcwalton): Including the shelf height here may be a bad API.
+    #[inline]
+    pub fn new(available_width: u32, shelf_height: u32) -> BatchBuilder {
+        BatchBuilder {
+            atlas: Atlas::new(available_width, shelf_height),
+            indices: vec![],
+            images: vec![],
+            point_count: 0,
+        }
+    }
+
+    pub fn add_glyph(&mut self,
+                     glyph_buffer_builder: &GlyphBufferBuilder,
+                     glyph_index: u32,
+                     point_size: f32)
+                     -> Result<(), ()> {
+        let descriptor = &glyph_buffer_builder.descriptors[glyph_index as usize];
+
+        // FIXME(pcwalton): I think this will check for negative values and panic, which is
+        // unnecessary.
+        let pixel_size = descriptor.pixel_rect(point_size).size.ceil().cast().unwrap();
+        let atlas_origin = try!(self.atlas.place(&pixel_size));
+
+        if self.point_count % POINTS_PER_SEGMENT == 0 {
+            self.indices.push(self.images.len() as u16)
+        }
+
+        self.images.push(ImageDescriptor {
+            atlas_x: atlas_origin.x,
+            atlas_y: atlas_origin.y,
+            point_size: point_size,
+            glyph_index: glyph_index,
+            start_point_in_glyph: descriptor.start_point,
+            start_point_in_batch: self.point_count,
+            point_count: descriptor.point_count as u32,
+        });
+
+        self.point_count += descriptor.point_count as u32;
+
+        Ok(())
+    }
+
+    pub fn finish(&mut self, device: &mut Device) -> Result<Batch, ()> {
+        let indices = BufferData::HostAllocated(HostAllocatedData::new(&self.indices));
+        let images = BufferData::HostAllocated(HostAllocatedData::new(&self.images));
+        Ok(Batch {
+            indices: try!(device.create_buffer(Protection::ReadOnly, indices).map_err(drop)),
+            images: try!(device.create_buffer(Protection::ReadOnly, images).map_err(drop)),
+        })
+    }
+}
+
+pub struct Batch {
+    pub indices: Buffer,
+    pub images: Buffer,
+}
+
 #[derive(Clone, Copy, Debug)]
 pub struct GlyphRange {
     pub start: u16,
@@ -45,22 +118,15 @@ impl Iterator for GlyphRangeIter {
     }
 }
 
-#[derive(Clone, Debug)]
-pub struct FontGlyphRange {
-    pub font_id: u32,
-    pub ranges: Vec<GlyphRange>,
-}
-
-#[derive(Clone)]
-pub struct FontGlyphRanges {
-    pub fonts: Vec<FontGlyphRange>,
-}
-
-impl FontGlyphRanges {
-    pub fn new() -> FontGlyphRanges {
-        FontGlyphRanges {
-            fonts: vec![],
-        }
-    }
+#[repr(C)]
+#[derive(Clone, Copy, Debug)]
+pub struct ImageDescriptor {
+    atlas_x: u32,
+    atlas_y: u32,
+    point_size: f32,
+    glyph_index: u32,
+    start_point_in_glyph: u32,
+    start_point_in_batch: u32,
+    point_count: u32,
 }
 

src/glyph_buffer.rs

@@ -8,38 +8,30 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use compute_shader::buffer::Buffer;
+use compute_shader::buffer::{Buffer, BufferData, HostAllocatedData, Protection};
+use compute_shader::device::Device;
+use euclid::{Point2D, Rect, Size2D};
 use otf::glyf::GlyfTable;
 use otf::loca::LocaTable;
 
-pub struct GlyphBuffers {
+pub struct GlyphBufferBuilder {
     pub coordinates: Vec<(i16, i16)>,
     pub operations: Vec<u8>,
     pub descriptors: Vec<GlyphDescriptor>,
-    pub cached_coordinates_buffer: Option<Buffer>,
-    pub cached_operations_buffer: Option<Buffer>,
-    pub cached_descriptors_buffer: Option<Buffer>,
 }
 
-impl GlyphBuffers {
+impl GlyphBufferBuilder {
     #[inline]
-    pub fn new() -> GlyphBuffers {
-        GlyphBuffers {
+    pub fn new() -> GlyphBufferBuilder {
+        GlyphBufferBuilder {
             coordinates: vec![],
             operations: vec![],
             descriptors: vec![],
-            cached_coordinates_buffer: None,
-            cached_operations_buffer: None,
-            cached_descriptors_buffer: None,
         }
     }
 
     pub fn add_glyph(&mut self, glyph_id: u32, loca_table: &LocaTable, glyf_table: &GlyfTable)
                      -> Result<(), ()> {
-        self.cached_coordinates_buffer = None;
-        self.cached_operations_buffer = None;
-        self.cached_descriptors_buffer = None;
-
         let mut point_index = self.coordinates.len() / 2;
         let mut operations = if point_index % 4 == 0 {
             0
@@ -70,8 +62,29 @@ impl GlyphBuffers {
             self.operations.push(operations)
         }
 
+        // TODO(pcwalton): Add a glyph descriptor.
+
         Ok(())
     }
+
+    pub fn finish(&self, device: &mut Device) -> Result<GlyphBuffers, ()> {
+        let coordinates = BufferData::HostAllocated(HostAllocatedData::new(&self.coordinates));
+        let operations = BufferData::HostAllocated(HostAllocatedData::new(&self.operations));
+        let descriptors = BufferData::HostAllocated(HostAllocatedData::new(&self.descriptors));
+        Ok(GlyphBuffers {
+            coordinates: try!(device.create_buffer(Protection::ReadOnly, coordinates)
+                                    .map_err(drop)),
+            operations: try!(device.create_buffer(Protection::ReadOnly, operations).map_err(drop)),
+            descriptors: try!(device.create_buffer(Protection::ReadOnly, descriptors)
+                                    .map_err(drop)),
+        })
+    }
+}
+
+pub struct GlyphBuffers {
+    pub coordinates: Buffer,
+    pub operations: Buffer,
+    pub descriptors: Buffer,
 }
 
 #[repr(C)]
@@ -82,6 +95,15 @@ pub struct GlyphDescriptor {
     pub height: i16,
     pub units_per_em: u16,
     pub point_count: u16,
-    pub index_of_first_point: u32,
+    pub start_point: u32,
+}
+
+impl GlyphDescriptor {
+    #[inline]
+    pub fn pixel_rect(&self, point_size: f32) -> Rect<f32> {
+        let pixels_per_unit = point_size / self.units_per_em as f32;
+        Rect::new(Point2D::new(self.left as f32, self.bottom as f32),
+                  Size2D::new(self.width as f32, self.height as f32)) * pixels_per_unit
+    }
 }
 

src/lib.rs

@@ -25,8 +25,8 @@ extern crate test;
 
 pub mod atlas;
 pub mod batch;
-pub mod buffers;
 pub mod charmap;
+pub mod glyph_buffer;
 pub mod otf;
 pub mod rasterizer;
 mod util;